An operating room (OR) is considered to be one of the most costly functional areas within hospitals as well as its major profit center. It is known that managing an OR department is a challenging task, which requires the integration of many actors (e.g., patients, surgeons, nurses, technicians) who may have conflicting interests and priorities. Considering these aspects, this dissertation focuses on developing a simulation based methodology for scheduling operating rooms under uncertainty, which reflects the complexity, uncertainty and variability associated with surgery. We split the process of scheduling ORs under uncertainty into two main components. First, we designed a research roadmap for modeling surgical procedure duration (from incision to wound closure) based on the surgery volume and time variability. Then, using a real surgical dataset we modeled the procedure duration using parametric and distribution-free predictive methods. We found that Support Vector Regression performs better that Generalized Linear Models increasing the prediction accuracy on unseen data by at least 5.5%. Next, we developed a simulation based methodology for scheduling ORs through a case study. For that purpose, we initially built one day feasible schedules using the 60th, 70th, 80th, and 90th percentiles to allocate surgical procedures to ORs using four different allocation policies. We then used a discrete event simulation model to evaluate the robustness of these initial feasible schedules considering the stochastic duration of all the OR activities and the arrival of surgical emergency cases. We found that on average elective waiting almost doubled the time for the emergency cases. In addition, we observed that there is not a clear effect of how being more conservative in scheduling within each scheduling policy impacts the elective waiting times. By contrast, there is a clear effect of how the scheduling policy and scheduling percentile impact the emergency waiting times. Thus, as we increase the percentile, the waiting times for emergency cases remarkably increases under half of the scheduling policies but reflects a lesser impact under scheduling the other half. OR utilization and OR overtime in a "virtual" eight operating room hospital fluctuate between 67% and 88% and 97 and 111 minutes respectively. Moreover, we noticed that both performance metrics depend not only on the levels of the scheduling policy and scheduling percentile but also are strongly affected by the increase of the emergency arrival rate. Finally, we fit a multivariate-multiple-regression model using the output of the simulation model to assess the robustness of the model and the extent to which these results can be generalized to a single, aggregate hospital goal. Further research should include a true stochastic optimization model to integrate optimization techniques into simulation analysis.

Past studies often find that, upon arrival U.S. immigrants generally have favorable health profiles than native-born persons, but their health deteriorates with prolonged stay. The classical explanations of this phenomenon are healthy immigrant selection and negative acculturation. With the number of foreign-born people living in the United States reaching an all-time high, the health and financial costs of this “negative acculturation” is substantial. Meanwhile, the negative duration effect on health is contradictory to expectations from classic assimilation theory and what has been observed by labor economists. This study aims to empirically study the effect of duration on immigrant health, with particular attention given to how socioeconomic status differentiates the duration-health relationship. Results based on two national datasets confirmed that immigrants, especially recent arrivals, have a considerably lower risk of worse health relative to native-born adults. I also found that socioeconomic status plays an essential role in the varying level of initial health selectivity among immigrants. The analysis of the interaction effect between duration and SES reveals that duration effects on health vary significantly by socioeconomic status. High SES immigrants tend to experience a non-negative duration effect regardless of their length of U.S. residence, while immigrants with lower socioeconomic standing are more likely to experience a negative duration effect on health with longer duration. Moreover, this study also shows that the initial foreign-born advantages in health are typically larger for persons with low SES than for persons with high SES. However, little evidence suggests there is a health convergence between long-term immigrants and their native-born counterparts with similar socioeconomic status. Potential explanations and implications of these findings are also discussed. / text

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Since doi moi, Vietnam has made remarkable achievements in many frontiers. However, much effort needs to be done to further improve social and economic sectors, particularly in the context of increasing the number of uncertainties. In analyses using household surveys from Vietnam, this dissertation finds that there are discrepancies between monetary and multidimensional measures of poverty in the same time period and as well as over time. The results also show that an additional shock is not always important but physical and human assets are vital determinants of a household's poverty dynamics. Additionally, coping strategies are useful for households to recover from shocks. However, it is not always easy to identify the effects of coping strategies independently from other effects. The findings of this dissertation contribute to the increasing discussion of the discrepancies between monetary and multidimensional poverty, of the vulnerability to poverty, and of the resilience against shocks. They are also useful for evaluation and assessment of poverty alleviating policies in developing countries.

Objectives To assess physical fitness in pregnancy and to evaluate its effect on perceived health, back pain, blood pressure and duration of gestation. Also, to evaluate the effect of serum relaxin levels on blood pressure and duration of gestation. Material and methods A prospective cohort of 520 pregnant women were examined in early pregnancy and five months postpartum with regard to socio-demographic characteristics and estimated peak oxygen uptake (V̇O2 peak, est.). Serum concentrations of relaxin were carried out in early pregnancy. Physical exercise, possible back pain and blood pressure were measured repeatedly throughout pregnancy. Results Absolute V̇O2 peak, est. in early pregnancy was positively correlated to perceived health, which was lower during than after pregnancy. The average absolute V̇O2 peak, est. in early pregnancy of 2.4 l/minute was 0.02 l/minute less than the V̇O2 peak, est. postpartum, while regular physical exercise decreased throughout pregnancy. Absolute V̇O2 peak, est. in early pregnancy was not associated to the incidence of any low back pain location in pregnancy or postpartum, but inversely to intensity of back pain and diastolic blood pressure and positively with duration of gestation. Elevated serum relaxin levels were associated with decreased diastolic blood pressure and higher duration of gestation among women with miscarriage. Conclusions Perceived health, diastolic blood pressure and duration of gestation were positively affected by physical fitness while no effect was shown on the incidence of back pain. The effect of physical fitness on duration of gestation and diastolic blood pressure might have clinical implications as well as the increased serum relaxin levels on miscarriages.

In a number of electrical engineering problems, so-called "crossing points" -- the instants at which two continuous-time signals cross each other -- are of interest. Often, particularly in applications using a Digital Signal Processor (DSP), only periodic samples along with a partial statistical characterization of the signals are available. In this situation, we are faced with the following problem: Given limited information about these signals, how can we efficiently and accurately estimate their crossing points? / For example, an audio amplifier typically receives its input from a digital source decoded into regular samples (e.g. from MP3, DVD, or CD audio), or obtained from a continuous-time signal using an analog-to-digital converter (ADC). In a switching amplifier based on Pulse-Width Modulation (PWM) or Click Modulation (CM), a signal derived from the sampled audio is compared against a deterministic reference waveform; the crossing points of these signals control a switching power stage. Crossing-point estimates must be accurate in order to preserve audio quality. They must also be simple to calculate, in order to minimize processing requirements and delays. / We consider estimating the crossing points of a known function and a Gaussian random process, given uniformly-spaced, noisy samples of the random process for which the second-order statistics are assumed to be known. We derive the Maximum A-Posteriori (MAP) estimator, along with a Minimum Mean-Squared Error (MMSE) estimator which we show to be a computationally efficient approximation to the MAP estimator. / We also derive the Cramer-Rao bound (CRB) on estimator variance for the problem, which allows practical estimators to be evaluated against a best-case performance limit. We investigate several comparison estimators chosen from the literature. The structure of the MMSE estimator and comparison estimators is shown to be very similar, making the difference in computational expense between each technique largely dependent on the cost of evaluating various (generally non-linear) functions. / Simulations for both Pulse-Width and Click Modulation scenarios show the MMSE estimator performs very near to the Cramer-Rao bound and outperforms the alternative estimators selected from the literature.

Subject of investigation - thermal extermination of monocotyledonous weed plant (barnyard grass (echinochloa crus-galli (L.))) using hot water vapour. Ecological weed control in crops is very important for development of ecological agriculture economy. While carrying out thermal weed extermination, it was noticed that monocotyledonous weeds are difficult to exterminate (to affect) thermally. The analysis of thermal extermination of the monocotyledonous weed plant (barnyard grass (echinochloa crus-galli (L.))) using wet water vapour is presented in the work. On the basis of temperature spread regularities in barnyard grass tissues established, the main technological indexes of thermal weed extermination using wet water vapour, application of which enables the efficient and ecological control of this difficult to exterminate weed plant, were determined. The data obtained were analysed statistically using the two-factor dispersion analysis. Growth stage efficiency of barnyard grass not dependent on the thermal effect duration, thermal effect duration influence not dependent on growth stages, as well as their interaction was discussed. The aim of this work is investigation of the water vapour thermal impact on the weed plant barnyard grass (echinochloa crus-galli (L.)) in various growth stages, with the purpose of its thermal extermination.

Pastaruoju metu biodujų gamyba, gamybos technologijos yra gana aktualios. Biodujų gamyboje tikslinga taikyti naujausias technologijas norint padidinti biodujų išeigą. Darbo tikslas: Ištirti elektromagnetinių laukų stiprių (H) ir poveikio trukmių (τ) įtaką biodujų išeigai. Atlikus literatūros šaltinių analizę, kai kurie autoriai užsimena apie elektromagnetinių laukų poveikių įtaką biodujų išeigai. Eksperimentiniai tyrimai atlikti Aleksandro Stulginskio universiteto biodujų laboratorijoje. Baigiamajame darbe atliktų eksperimentinių tyrimų rezultatai rodo, kad elektromagnetinių laukų stipriai, šių laukų poveikio trukmė įtakoja biodujų išeigą. / Lately production of biogas and production technology is relevant. In biogas production it is appropriate to apply the newest technologies in order to increase biogas yield. The aim – to research electromagnetic fields strength (heart) and the durations of exposures (τ) influence on biogas yield. After literature analyzing, it was revealed that some authors talk about electromagnetic fields influence on biogas yield. Experimental research was done in university of Aleksandras Stulginskis, biogas laboratory. Thesis results of experimental research shows that electromagnetic fields strengths and that field’s duration of exposure have influence on biogas yield.

In this research, Communicative Accommodation Theory (CAT) is investigated while native speakers address nonnative peers. For the intentions of this research, three native speakers of Canadian English were asked to have conversations with native and nonnative peers. The conversations were in the form of giving directions on the map. Later on, the participants’ formants and vowel durations were measured and used for comparing native-nonnative peer effect(s) on the speakers’ vowel formants and duration. Based on the analyses, it is suggested that accommodation may take place based on providing stereotypical vowel durations and formants, as well as reducing inter-token variations in the nonnative peer context.

Galima teigti, jog ilgą laiką filosofija kino atžvilgiu buvo nusiteikusi priešiškai. Filosofai bei menininkai abejojo kino priklausomybe meno sričiai, nes kinas, anot jų, neturi savitos ir unikalios kalbos, o režisieriai piktinosi, jog filosofai, interpretuodami tam tikrus filmus, jiems primeta savas teorijas, taip atimdami iš kinematografinio meno jo unikalumą. Šio darbo tikslas – pažvelgti į kinematografinį meną iš filosofinės perspektyvos, o, tiksliau, kokias prielaidas interpretuojant kiną gali pasiūlyti filosofija. Aptariant tokius konceptus kaip – laikas, trukmė, kinematografinis mechanizmas, vaizdas, vaizdinys-judėjimas, vaizdinys-laikas, momentinės nuotraukos, montažas ir kt. – nuo filosofinės disciplinos pereinama prie kinematografinio meno, bei bandoma įrodyti, jog kinas, bent jau kartais, turi nemažai bendro su filosfinėmis teorijomis. Kino kuriami vaizdiniai gali tapti iliustracijomis filosofijos kuriamų konceptų. / We can say, that for a very long time, philosophy was bad-minded in regard to cinema. Philosophers and artists had doubts about cinema‘s subordination to art, because, in their opinion, cinema doesn‘t have his own, unique language, and film directors were in anger, because philosophers, in their interpretations of certain films, tried to enforce their own theories to cinema, by taking away its unique being. The aim of this work - to look into cinematic art from philosophical perspective, more precise, what assumptions of cinema interpretation can offer philosophy. Discussing concepts like – time, duration, cinematic mechanism, image, image-movement, image-time, snapshot, montage – we move from philosophical discipline to cinematic art, by trying to prove, that cinema has something common with philosophical theories. Images composed by cinema, can become illustrations of philosophical concepts.